Preserve domtree and loop-simplify for runtime unrolling.
Mostly straightforward changes; we just didn't do the computation before.
One sort of interesting change in LoopUnroll.cpp: we weren't handling
dominance for children of the loop latch correctly, but
foldBlockIntoPredecessor hid the problem for complete unrolling.
Currently punting on loop peeling; made some minor changes to isolate
that problem to LoopUnrollPeel.cpp.
Adds a flag -unroll-verify-domtree; it verifies the domtree immediately
after we finish updating it. This is on by default for +Asserts builds.
Differential Revision: https://reviews.llvm.org/D28073
llvm-svn: 292447
diff --git a/llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp b/llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
index 842cf31..f021617 100644
--- a/llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp
@@ -28,6 +28,7 @@
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/LoopSimplify.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
#include "llvm/Transforms/Utils/UnrollLoop.h"
#include <algorithm>
@@ -257,7 +258,7 @@
/// optimizations.
bool llvm::peelLoop(Loop *L, unsigned PeelCount, LoopInfo *LI,
ScalarEvolution *SE, DominatorTree *DT,
- bool PreserveLCSSA) {
+ AssumptionCache *AC, bool PreserveLCSSA) {
if (!canPeel(L))
return false;
@@ -404,10 +405,20 @@
LatchBR->setMetadata(LLVMContext::MD_prof, WeightNode);
}
+ // FIXME: Incrementally update domtree.
+ DT->recalculate(*L->getHeader()->getParent());
+
// If the loop is nested, we changed the parent loop, update SE.
- if (Loop *ParentLoop = L->getParentLoop())
+ if (Loop *ParentLoop = L->getParentLoop()) {
SE->forgetLoop(ParentLoop);
+ // FIXME: Incrementally update loop-simplify
+ simplifyLoop(ParentLoop, DT, LI, SE, AC, PreserveLCSSA);
+ } else {
+ // FIXME: Incrementally update loop-simplify
+ simplifyLoop(L, DT, LI, SE, AC, PreserveLCSSA);
+ }
+
NumPeeled++;
return true;